On Tuesday 18 March 2014 11:24 AM, Vinod Koul wrote: > On Mon, Mar 17, 2014 at 03:37:47PM -0400, Santosh Shilimkar wrote: >>>> To simplify this bit more, you can think of this as DMA channels, flows >>>> are allocated and DMA channels are enabled by DMA engine and they remains >>>> enabled always as long as the channel in use. Enablling dma channel >>>> actually don't start the DMA transfer but just sets up the connection/pipe >>>> with peripheral and memory and vice a versa. >>>> >>>> All the descriptor management, triggering, sending completion interrupt or >>>> hardware signal to DMAEngine all managed by centralised QMSS. >>>> >>>> Actual copy of data is still done by DMA hardware but its completely >>>> transparent to software. DMAEngine hardware takes care of that in the >>>> backyard. >>> So you will use the dmaengine just for setting up the controller. Not for actual >>> transfers. Those would be governed by the QMSS, right? >>> >> Correct. >> >>> This means that someone expecting to use dmaengine API will get confused about >>> this and doing part (alloc) thru dmaengine and rest (transfers) using some other >>> API. This brings to me the design approach, does it really make sense creating >>> dmaengine driver for this when we are not fully complying to the API >>> >> Thats fair. The rationale behind usage of DMEngine was that its the closest >> available subsystem which can be leveraged for this hardware. We can >> pretty much use all the standard DMAEngine device tree parsing as well as >> the config API to setup DMAs. >> >> I think you made your stand clear, just to confirm, you don't prefer this >> driver to be a DMAEngine driver considering it doesn't fully complying to >> the APIs. We could document the deviation of 'transfer' handling to avoid >> any confusion. > Yup, a user will just get confused as the driver doenst conform the dmaengine > API. Unless someone comes up witha strong argument on why it should be > dmaengine driver and what befits we see form such a model, i would like a > damengine driver to comply to standard API and usage. > OK thanks !! Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
